TWI624906B - High dielectric constant dielectric layer forming method, image sensor device, and manufacturing method thereof - Google Patents

Abstract

A method for forming a high-k dielectric layer on a substrate includes introducing a chloride precursor on a surface of the substrate. An oxidant is introduced to the surface to form a high-k dielectric layer on the substrate. The high-k dielectric layer has a chlorine concentration of less than about 8 atoms / cm3.

Description

Method for forming high-k dielectric layer and image Sensing device and manufacturing method thereof

This disclosure relates to an image sensing device.

Integrated circuit (IC) technology is continuously improved. These improvements often involve scaling down the device geometry to achieve lower manufacturing costs, higher device integration density, higher speed, and better performance. Not only realize the advantages from reducing the geometry size, but also directly improve the IC device. Such an IC device is an image sensing device. The image sensing device includes a pixel array (or grid) for detecting light and recording the intensity (brightness) of the detected light. Pixel arrays respond to light by accumulating charge--for example, the higher the intensity of light, the higher the charge accumulated in the pixel array. The accumulated charge is then used (for example by other circuits) to provide color and brightness for suitable applications such as digital cameras.

One type of image sensing device is a bacκside illuminated (BSI) image sensing device. For back-illuminated image sensor The volume of light projected on the back surface of the sensing substrate (which supports the backside illuminated image sensor circuit of the image sensor device). The pixel grid is located on the front side of the substrate, and the substrate is thin enough so that light projected toward the back side of the substrate can reach the pixel grid. Compared with a front-side illuminated (FSI) image sensing device, a back-illuminated image sensing device provides a high fill factor and reduced harmful interference. Due to the reduction in device size, improvements in back-illuminating technology continue to improve the image quality of back-illuminated image sensing devices.

According to some embodiments of the present disclosure, a method for forming a high-k dielectric layer on a substrate includes introducing a chloride precursor on a surface of the substrate. An oxidant is introduced to the surface to form a high-k dielectric layer on the substrate. The high-k dielectric layer has a chlorine concentration of less than about 8 atoms / cm3.

According to some embodiments of the present disclosure, a method for manufacturing an image sensing device includes forming a light sensing region in a substrate. The light sensing area faces the front surface of the substrate. Using an atomic layer deposition process, a high-k dielectric layer is formed on the back surface of the substrate opposite the front surface. The precursor of the atomic layer deposition process includes chloride, and an oxidant is introduced during the atomic layer deposition process substantially equal to or greater than about 0.5 seconds.

According to some embodiments of the present disclosure, the image sensing device includes a substrate and a high-k dielectric layer. The substrate has a front surface and a back surface opposite to the front surface. The substrate further has a light sensing area facing the front surface. High dielectric The coefficient dielectric layer is disposed on the back surface of the substrate. The high-k dielectric layer has a chlorine concentration of less than about 8 atoms / cm3.

According to the above embodiment, the high-k dielectric layer can be formed using an atomic layer deposition process. Chloride precursors are used to form high-k dielectric layers. Since the oxidant is introduced during the atomic layer deposition process that is substantially equal to or greater than about 0.5 seconds, the chloride of the chloride precursor can be effectively replaced by the ion of the oxidant, so that the chlorine of the formed high-k dielectric layer The concentration can be reduced to less than about 8 atoms / cm3. The low chlorine concentration improves the layering problem of the high-k dielectric layer and increases the adhesion between the high-k dielectric layer and the substrate.

102‧‧‧light sensing area

110‧‧‧ substrate

112‧‧‧ front surface

114‧‧‧back surface

120‧‧‧Isolation characteristics

130‧‧‧Interconnection Structure

132‧‧‧through hole

134‧‧‧line

140‧‧‧ buffer layer

150‧‧‧ carrier wafer

160‧‧‧High dielectric constant dielectric layer

162‧‧‧ metal oxide bonding

170‧‧‧ color filters

202, 204, 206‧‧‧ line segments

210‧‧‧Chloride precursors

220‧‧‧Oxidant

P‧‧‧pixel

The aspect of this disclosure will be well understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that according to standard practice in the industry, features are not drawn to scale. In fact, the size of each feature can be arbitrarily increased or decreased for clarity of discussion.

1A to 1F are cross-sectional views of a method for manufacturing an image sensing device at various stages according to some embodiments of the present disclosure.

Fig. 2 is a graph showing the concentration of each atom with respect to the depth of the color filter, the high dielectric constant dielectric layer and the substrate of the image sensing device of Fig. 1F.

The following disclosure provides many different embodiments or examples to implement different features of the provided subject matter. The specifics of components and arrangements are described below Examples to simplify this disclosure. Of course, these examples are merely examples and are not intended to be limiting. For example, forming the first feature above or on the second feature in the following description may include embodiments in which the first feature and the second feature are formed by direct contact, and may also include an embodiment in which the first feature and the second feature are formed. Embodiments in which additional features are formed so that the first feature and the second feature may not be in direct contact. In addition, the disclosure may repeat component symbols and / or letters in each example. This repetition is for conciseness and clarity, and does not in itself indicate the relationship between the embodiments and / or configurations discussed.

Further, for the convenience of description, spatially relative terms (such as "below", "below", "lower", "above", "upper", and the like) may be used to describe an element illustrated in the figures. The relationship of a feature or features to another element (or features) or feature (or features). In addition to the orientations depicted in the figures, spatially relative terms are intended to encompass different orientations of the device in use or operation. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and therefore the spatially relative descriptors used herein may also be interpreted as such.

In some embodiments of forming a back-illuminated (BSI) image sensing device, a high dielectric constant (high κ) dielectric layer is formed on a substrate to become a bottom anti-reflective coating on the image sensing device. coating; BARC) layer. The bottom anti-reflection coating layer formed by the high-dielectric-constant dielectric layer has the ability to accumulate charges, which improves the quality problems of dark current, white pixels, and dark image non-uniformity (DINU). In some embodiments, the high-k dielectric layer is formed by an atomic layer deposition process and uses a metal chloride as a precursor. High dielectric The chlorine concentration of the dielectric constant layer is related to the adhesion between the high dielectric constant layer and the substrate. In order to improve the adhesion and delamination of the high-k dielectric layer, an image sensing device and a manufacturing method thereof are provided in the following paragraphs.

1A to 1F are cross-sectional views of a method for manufacturing an image sensing device at various stages according to some embodiments of the present disclosure. The image sensing device includes an array of pixels P, and the pixels P can be arranged in rows and columns. The word "pixel" indicates a basic unit containing a feature for converting electromagnetic radiation into an electrical signal (for example, it may include a photodetector of each semiconductor device and each circuit). For simplicity, the image sensing device includes a single pixel P as described in this disclosure; however, an array of these pixels can generally form the image sensing device illustrated in FIG. 1A.

The pixel P may include a photodiode, a complementary metal oxide semiconductor (CMOS) image sensing device, a charged coupled device (CCD) sensor, an active sensor, and a passive sensor , Other sensors, or a combination of the above. The pixels P may be designed to have various sensor types. For example, one group of pixels P may be a CMOS image sensing device and another group of pixels P may be a passive sensor. In addition, the pixel P may include a color image sensing device and / or a monochrome image sensing device. In an example, the at least one pixel P is, for example, an active pixel sensor of a CMOS image sensing device. In FIG. 1A, the pixel P may include a photodetector (such as a photogate type photodetector) for recording the intensity or brightness of light (radiation). The pixel P may also include various semiconductor devices, such as a transfer transistor, a reset transistor, a source follower transistor, a selection transistor, other suitable transistors, or Each transistor is a combination of the above. Additional circuits, inputs and / or outputs can be coupled to the pixel array to provide an operating environment for the pixel P, and support external communication with the pixel P. For example, the pixel array may be coupled with a readout circuit and / or a control circuit. However, the pixels P drawn with the same schematic diagram may be different from each other to have different joint surface depths, thicknesses, widths, and the like.

In FIG. 1A, the image sensing device is a back-illuminated image sensing device. The image sensing device may be an integrated circuit (IC) chip, a system on chip (SoC), or a part thereof. The chip or system includes various passive and active microelectronic components, such as resistors, capacitors, and inductors. Devices, diodes, metal-oxide-semiconductor field effect transistors (MOSFETs), CMOS transistors, bipolar junction transistors (BJTs), lateral diffusion MOS (laterally diffused MOS; LDMOS) transistors, high-power MOS transistors, fin-liκe field effect transistors (FinFETs), other suitable components, or combinations thereof. For clarity, Figure 1A has been simplified to better understand the inventive concepts of this disclosure. Additional features may be added to the image sensing device, and for other implementations of the image sensing device, some of the features described below may be replaced or eliminated.

The image sensing device includes a substrate 110 having a front surface 112 and a back surface 114. In FIG. 1A, the substrate 110 is a semiconductor substrate including silicon. Alternatively or in addition, the substrate 110 includes another element semiconductor such as germanium and / or diamond; a compound semiconductor including silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide, and / or indium antimonide; Contains silicon germanium (SiGe), phosphorus arsenic Alloys of gallium (GaAsP), indium aluminum arsenide (AlInAs), aluminum gallium arsenide (AlGaAs), indium gallium arsenide (GaInAs), indium gallium phosphide (GaInP), and / or indium gallium phosphide (GaInAsP) Semiconductor; or a combination thereof. The substrate 110 may be a semiconductor on insulator (SOI). The substrate 110 may include a gradient semiconductor layer and / or a semiconductor layer covering another semiconductor layer of a different type, such as a silicon layer on a silicon germanium layer. In FIG. 1A, the substrate 110 may be a p-type substrate. The p-type dopants doped on the substrate 110 include boron, gallium, indium, other suitable p-type dopants, or a combination thereof. The substrate 110 may alternatively be an n-type doped substrate. The n-type dopants that can be doped on the substrate 110 include phosphorus, arsenic, other suitable n-type dopants, or a combination thereof. The substrate 110 may include respective p-type doped regions and / or n-type doped regions. Doping can be performed in various steps and techniques using processes such as ion implantation or diffusion. The thickness of the substrate 110 may range between approximately 100 micrometers (μns) and approximately 3000 micrometers.

The substrate 110 includes isolation features 120 such as local oxidation of silicon (LOCOS) and / or shallow trench isolation (STI) to separate (or isolate) the substrate 110 or the substrate Areas and / or devices within 110. For example, the isolation feature 120 isolates a pixel P from an adjacent pixel. In FIG. 1A, the isolation feature 120 is an STI. The isolation feature 120 includes silicon oxide, silicon nitride, silicon oxynitride, other insulating materials, or a combination thereof. The isolation feature 120 is formed by any suitable process. As some examples, forming an STI includes a photolithography process, etching a trench in a substrate (for example, by using dry etching, wet etching, or a combination thereof), and using one or more dielectric materials Fill the trench (for example, by using a chemical vapor deposition process). In some examples, the filled trench may have a multilayer structure, such as a thermally oxidized pad layer filled with silicon nitride or silicon oxide. In some other examples, the STI structure can be made by the following process sequence: forming a pad oxide, forming a low pressure chemical vapor deposition (LPCVD) nitride layer over the pad oxide, using a photoresist and a mask The mask is used to pattern the STI openings in the pad oxide and nitride layers. The trenches in the substrate are etched in the STI openings. If necessary, a thermally oxidized trench pad is generated to improve the trench interface. A chemical mechanical polishing (CMP) process is performed to etch back and planarize, and a nitride lift-off process is used to remove the nitride layer.

As mentioned above, the pixels P are formed in the substrate 110. The pixel P detects a radiation intensity (brightness) directed toward the back surface 114 of the substrate 110. The incident radiation is visible light. Alternatively, the radiation is infrared (IR), ultraviolet (UV), x-ray, microwave, other suitable radiation types, or a combination thereof. The pixels P may be configured to correspond to specific light wavelengths such as red, green, or blue light wavelengths. In other words, the pixel P may be configured to detect the intensity (brightness) of a specific wavelength of light. In FIG. 1A, the pixel P includes a photodetector such as a photodiode. The photodetector includes a light sensing area (or a photon sensing area) 102. The light sensing region 102 is a doped region having n-type and / or p-type dopants formed in the substrate 110 along the front surface 112 of the substrate 110 so that the light sensing region 102 faces the front surface 112. In FIG. 1A, the light sensing region 102 may be an n-type doped region. The light sensing region 102 is formed by a method such as diffusion and / or ion implantation. In spite of Not shown in Figure 1A, the pixel P further includes various transistors, such as a transfer transistor associated with a transfer gate, a reset transistor associated with a reset gate, a source follower transistor, and a selection transistor , Other suitable transistors, or a combination of the above. The light-sensing area 102 and the transistors (which may be collectively referred to as a pixel circuit) allow the pixel P to detect the intensity of a specific light wavelength. Additional circuits, inputs and / or outputs may be supplied to the pixel P to provide an operating environment for the pixel P and / or support communication with the pixel P.

Subsequently, the interconnection structure 130 is formed above the front surface 112 of the substrate 110 and is included above the pixels P. The interconnect structure 130 is coupled to each component of the back-illuminated image sensing device, such as the pixel P, so that each component of the back-illuminated image sensing device is operable to appropriately respond to irradiation light (image radiation). The interconnect structure 130 may include a plurality of patterned dielectric layers and conductive layers that provide various doped features of the image sensing device, interconnection (eg, wiring) between the circuit and the input / output. The interconnect structure 130 may further include an interlayer dielectric (ILD) and a multilayer interconnect (MLI) structure. In FIG. 1A, the interconnect structure 130 includes various conductive features, which may be, for example, vertical interconnections of the vias 132 and / or horizontal interconnections such as the lines 134. Each conductive feature (ie, the vias 132 and lines 134) includes a conductive material such as a metal. In some examples, metals including aluminum, aluminum / silicon / copper alloys, titanium, titanium nitride, tungsten, polycrystalline silicon, metal silicides, or combinations thereof may be used. In some implementations, each conductive feature (ie, vias 132 and lines 134) may be referred to as an aluminum interconnect. Aluminum interconnects can be fabricated by physical vapor deposition (PVD), chemical vapor deposition (CVD), or a combination thereof. 程 formation. Other manufacturing techniques for forming the conductive features (ie, the vias 132 and the lines 134) may include photolithography and etching to pattern the conductive material to form vertical and horizontal connections. Other manufacturing processes can still be implemented to form the interconnect structure 130, and other manufacturing processes such as thermal annealing to form metal silicide. The metal silicide used for the multilayer interconnection may include nickel silicide, cobalt silicide, tungsten silicide, tantalum silicide, titanium silicide, platinum silicide, hafnium silicide, palladium silicide, or a combination thereof. Alternatively, each conductive feature (i.e., the vias 132 and lines 134) may be a copper multilayer interconnect including copper, copper alloy, titanium, titanium nitride, tantalum, tantalum nitride, tungsten, polycrystalline silicon, Metal silicide, or a combination of the above. The copper interconnect may be formed by a process including PVD, CVD, or a combination thereof. It should be understood that the illustrated conductive features (ie, the vias 132 and lines 134) are exemplary, and the actual positioning and configuration of the conductive features (ie, the vias 132 and lines 134) may depend on the design requirements. different.

In some embodiments, a buffer layer 140 may be formed on the interconnect structure 130. In FIG. 1A, the buffer layer 140 includes a dielectric material such as silicon oxide. Alternatively, the buffer layer 140 may include silicon nitride as required. The buffer layer 140 is formed by CVD, PVD, or other suitable techniques. The buffer layer 140 may be planarized by a CMP process to form a smooth surface.

Subsequently, the carrier wafer 150 may be further bonded to the substrate 110 via the buffer layer 140, thereby performing a process on the back surface 114 of the substrate 110. In this embodiment, the carrier wafer 150 is similar to the substrate 110 and includes a silicon material. Alternatively, the carrier wafer 150 may include a glass substrate or another suitable material. The carrier wafer 150 can be bonded to the substrate 110 by molecular force--this molecular force is Techniques called direct bonding or photo-fusion bonding-or other bonding techniques known in the art by, for example, metal diffusion or anodic bonding.

The buffer layer 140 provides electrical isolation between the substrate 110 and the carrier wafer 150. The carrier wafer 150 provides protection of features such as the pixels P formed on the front surface 112 of the substrate 110. The carrier wafer 150 also provides mechanical strength and supports the back surface 114 of the processing substrate 110 as discussed below. After bonding, the substrate 110 and the carrier wafer 150 may be annealed as needed to enhance the bonding strength.

Please refer to Figure 1B. After the CMOS process is completed on the front surface 112 of the substrate 110, the substrate 110 is flipped from the back surface 114 to perform a thinning process to thin the substrate 110. The thinning process may include a mechanical grinding process and a chemical thinning process. During the mechanical polishing process, a large amount of substrate material may be removed from the substrate 110 first. Thereafter, the chemical thinning process may apply an etching chemical to the back surface 114 of the substrate 110 to further thin the substrate 110 to a desired thickness. When the substrate 110 is a SOI type, a buried oxide layer (BOX) can serve as an etch stop layer. The thickness of the substrate 110 of the back-illuminated image sensing device is about 5-10 microns. In some embodiments, the thickness can be less than about 5 microns, and even reduced to about 2-3 microns. The thickness of the substrate 110 may be implemented depending on the application type of the image sensing device.

Subsequently, a high-k dielectric layer 160 (see FIG. 1E) is formed on the back surface 114 of the substrate 110. The high-k dielectric layer 160 may be a bottom anti-reflective coating (BARC) layer of the image sensing device. In more detail, a pre-cleaning process of the back surface 114 of the substrate 110 may be performed to remove the native oxide on the back surface 114 to generate a hydrogen end group (OH) surface. This can be used Diluted hydrofluoric acid (DHF) treatment or vapor hydrofluoric acid (VHF) treatment is achieved for a suitable time.

Please refer to Figures 1C and 1D. The pulse of introducing the chloride precursor 210 on the back surface 114 of the substrate 110 reaches the first period. In some embodiments, the chloride precursor is a metal chloride such as lanthanum chloride (LaCl ₃ ), hafnium tetrachloride (HfCl ₄ ), or zirconium tetrachloride (ZrCl ₄ ) Compound. The chloride precursor 210 of FIG. 1C reacts with the OH surface (ie, the back surface 114) to form a metal oxide bond 162 as shown in FIG. 1D. The non-reactive portion of the chloride precursor 210 is removed from the back surface 114. In some embodiments, the first period is from about 0.5 seconds to about 2 seconds, depending on the actual situation.

Please refer to Figures 1D and 1E. The oxidant 220 is then introduced to the back surface 114 for a second period of time. In some embodiments, the oxidant 220 is water (H ₂ O). Water molecules react with the metal oxide junction 162. The chloride of the metal oxide junction 162 can be replaced by the OH ion of water to form the high-k dielectric layer 160 as shown in FIG. 1E. In some embodiments, the high-k dielectric layer 160 is made of lanthanum oxide, hafnium oxide, zirconia, or a combination thereof. The dielectric constant of the high dielectric constant dielectric layer 160 is higher than that of SiO ₂ , that is, the dielectric constant is greater than about 3.9. For example, by introducing a chloride precursor to react with the surface of the OH end groups, the process cycle can continue. In some embodiments, the second period is equal to or greater than about 0.5 seconds. In some other embodiments, the second period is about 0.5 seconds to about 1.5 seconds, depending on the actual situation.

In some embodiments, after the oxidant 220 is introduced, another oxidant may be introduced to the back surface 114 to further replace the chloride of the metal oxide junction 162 for a second period of time. The oxidant may be ozone. Since the chloride is effectively replaced, the chloride of the high-k dielectric layer 160 is further reduced. In some embodiments, the chlorine concentration of the high-k dielectric layer is less than about 8 atoms / cm ³ . In some other embodiments, the chlorine concentration of the high-k dielectric layer is less than about 5 atoms / cubic centimeter.

During the manufacturing process of the image sensing device, if water is used, the water will dissociate and release hydrogen ions, and these hydrogen ions react with chlorides to form hydrochloric acid (HCl). Hydrochloric acid will corrode the high-k dielectric layer 160, thereby reducing the adhesion between the high-k dielectric layer 160 and the substrate 110, and causing the high-k dielectric layer 160 to delaminate. However, in Fig. 1E, since the chlorine concentration of the high-dielectric-constant dielectric layer 160 is lower than about 8 atoms / cm3, the concentration of hydrochloric acid formed is relatively low. Therefore, the adhesion and delamination problems can be improved as shown in Table 1 below.

Table 1 shows the experimental results of the layered defect density between the high-k dielectric layer and the substrate. In Table 1, the high-k dielectric layer is made of hafnium oxide (HfO ₂ ), the substrate is made of silicon, and the chloride precursor is hafnium tetrachloride (HfCl ₄ ). Table 1 shows that when the second period is increased, the chlorine (Cl) concentration decreases, and when the chlorine concentration of the high-k dielectric layer is low, the defect density decreases. For example, when the second period is about 0.5 seconds, the chlorine concentration is reduced to about 8 atoms / cm3, and the defect density is reduced from about 55 numbers / square millimeter (NO./mm ² ) to about 16 numbers / square. Mm. In addition, when the second period is about 1.5 seconds, the chlorine concentration is reduced to about 5 atoms / cubic centimeter, and the defect density is further reduced to about 0 number / square millimeter.

Please refer to Figure 1E. The high-dielectric constant dielectric layer 160 as a BARC layer mainly has a cumulative charge (mainly a negative charge but a positive charge in some cases). The charge accumulation ability of the high-dielectric constant dielectric layer 160 improves the dark current, white pixels, and dark image non-uniformity (DINU) quality problems. This dark current flows into the image sensing device when the image sensing device lacks incident light Current. This white pixel occurs when an excessive current leak causes an abnormally high signal from the pixel. When the high-dielectric constant dielectric layer 160 has negative (positive) charge accumulation, it attracts the positive (negative) electric charges in the substrate 110 to the high-dielectric constant dielectric layer 160 / substrate 110 interface to form an electric dipole. That is, where the negative (positive) charge increases Holes (electrons) accumulate in the interface and create empty areas at or near the interface. The electric dipole functions as a charge barrier layer, trapping imperfections or defects such as dangling bonds.

Please refer to Figure 1F. Additional processing may be performed to complete the manufacturing of the image sensing device. For example, a passivation layer may be formed around the image sensing device for protection (for example, dust or moisture). The color filter 170 is formed on the high-k dielectric layer 160 and is aligned with the light sensing region 102 of the pixel P. The color filter 170 may be positioned such that incoming light is directed directly onto and through the color filter 170. The color filter 170 may include a dye-based (or pigment-based) polymer or resin for filtering a specific wavelength band of incoming light, the specific wavelength band corresponding to a color spectrum (for example, red, green, and blue).

In some embodiments, a micro-lens is formed on the color filter 170 to direct and focus incoming light toward a specific radiation-sensing area in the substrate 110, such as the pixel P. Microlenses can be positioned in various arrangements and have various shapes, depending on the refractive index of the material used for the microlenses and the distance from the sensor surface. It should also be understood that the substrate 110 may also undergo an optional laser annealing process before the color filters 170 or microlenses are formed.

FIG. 2 is a graph showing the concentration of each atom with respect to the depth of the color filter 170, the high dielectric constant dielectric layer 160, and the substrate 110 of the image sensing device of FIG. 1F. In FIG. 2, the color filter 170 is made of an oxide, the high-k dielectric layer 160 is made of HfO ₂ , and the substrate 110 is made of silicon. Line 202 indicates the concentration of chlorine, line 204 indicates the concentration of fluoride, and line 206 indicates the concentration of carbon. In Fig. 2, the chlorine concentration is lower than 1 atom / cm3.

According to the above embodiment, the high-k dielectric layer can be formed using an atomic layer deposition process. Chloride precursors are used to form high-k dielectric layers. Since the oxidant is introduced during the atomic layer deposition process that is substantially equal to or greater than about 0.5 seconds, the chloride of the chloride precursor can be effectively replaced by the ion of the oxidant, so that the chlorine of the formed high-k dielectric layer is The concentration can be reduced to less than about 8 atoms / cm3. The low chlorine concentration improves the layering problem of the high-k dielectric layer and increases the adhesion between the high-k dielectric layer and the substrate.

According to some embodiments of the present disclosure, a method for forming a high-k dielectric layer on a substrate includes introducing a chloride precursor on a surface of the substrate. An oxidant is introduced to the surface to form a high-k dielectric layer on the substrate. The high-k dielectric layer has a chlorine concentration of less than about 8 atoms / cm3.

According to some embodiments of the present disclosure, a method for manufacturing an image sensing device includes forming a light sensing region in a substrate. The light sensing area faces the front surface of the substrate. Using an atomic layer deposition process, a high-k dielectric layer is formed on the back surface of the substrate opposite the front surface. The precursor of the atomic layer deposition process includes chloride, and an oxidant is introduced during the atomic layer deposition process substantially equal to or greater than about 0.5 seconds.

According to some embodiments of the present disclosure, the image sensing device includes a substrate and a high-k dielectric layer. The substrate has a front surface and a back surface opposite to the front surface. The substrate further has a light sensing area facing the front surface. A high-k dielectric layer is disposed on the back surface of the substrate. The high-k dielectric layer has a chlorine concentration of less than about 8 atoms / cm3.

The features of the embodiments are summarized above, so that those skilled in the art can better understand the aspects of the present disclosure. Those skilled in the art should understand that the disclosure can be easily used as a basis for designing or modifying other processes and structures in order to implement the same purpose and / or achieve the same advantages of the embodiments described herein. Those skilled in the art should also realize that such equivalent structures have not deviated from the spirit and scope of this disclosure, and can have various changes, substitutions and alterations without departing from the spirit and scope of this disclosure.

Claims (10)

A method of forming a high-k dielectric layer on a substrate, comprising: processing the substrate to form a hydrogen end group (OH) surface on a surface of the substrate; introducing a chloride precursor on the surface Material, so that the chloride precursor reacts with the surface of the hydrogen end group (OH); and after the chloride precursor reacts with the surface of the hydrogen end group (OH), an oxidant is introduced on the surface to the substrate The high-k dielectric layer is formed thereon. The method of claim 1, wherein the chloride precursor is a metal chloride. The method according to claim 1, wherein the substrate is made of silicon. The method according to claim 1, wherein the processing the substrate to form the hydrogen end group (OH) surface on the surface of the substrate comprises: performing a pre-cleaning process on the surface of the substrate. A method for manufacturing an image sensing device, the method includes: forming a light sensing area in a substrate, wherein the light sensing area faces a front surface of the substrate; and processing the substrate to form a hydrogen end group An (OH) surface on a back surface opposite to the front surface in the substrate; and using an atomic layer deposition process to form a high-k dielectric layer on the back surface, wherein the atomic layer deposition process A precursor containing a chloride is introduced in a first period so that the precursor reacts with the surface of the hydrogen end group (OH), and an oxidant is introduced in a second period to form the high dielectric on the substrate. A dielectric layer, and the second period is performed after the first period. The method according to claim 5, wherein the precursor further includes hafnium (Hfnium), zirconium (Zr), lanthanum (La), or a combination thereof. The method according to claim 5, wherein the atomic layer deposition process comprises: removing a native oxide on the back surface of the substrate. An image sensing device includes: a substrate having a front surface and a back surface opposite to the front surface, wherein the substrate further has a light sensing area facing the front surface; and a high dielectric constant dielectric Layer on the back surface of the substrate, wherein the chlorine concentration of one of the high-k dielectric layers is lower than about 8 atoms / cm3. The image sensing device according to claim 8, wherein the high-k dielectric layer is made of lanthanum oxide, hafnium oxide, zirconia, or a combination thereof. The image sensing device according to claim 8, wherein the material of the substrate is silicon.